From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 127585 invoked by alias); 18 Mar 2015 01:21:51 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 127520 invoked by uid 48); 18 Mar 2015 01:21:47 -0000 From: "adam at consulting dot net.nz" To: gcc-bugs@gcc.gnu.org Subject: [Bug inline-asm/65436] Max number of extended asm +output operands currently limited to 15 Date: Wed, 18 Mar 2015 01:21:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: inline-asm X-Bugzilla-Version: unknown X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: adam at consulting dot net.nz X-Bugzilla-Status: RESOLVED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2015-03/txt/msg01748.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65436 --- Comment #6 from Adam Warner --- Sorry, I did not mean to send my previous comment. I updated the title and a hasty comment I was about to edit got added. It is unfair to dismiss my enhancement request as invalid. I correctly explained the current limitation (which happens to match the documentation!), proposed raising the limit from 30 to 80+ (marked as an enhancement request), and provided code which tests a limit up to 2x39=78 double-counted operands. I'm told it is too costly to raise this limit due to the way gcc handles asm operands internally. I think this is will-not-fix territory due to the current architecture of gcc. How does clang manage to compile the same code? I know of no public code where gcc's 15/30 asm operand limit has been a problem. The limitations I'm hitting in private code are naturally not your primary, secondary nor even tertiary concern. The limitation will only be important if the technique is used in a popular project where benchmark competition across compilers encourages gcc to remove the limitation.